Gen5 Prius -- EGR cleaning required?

shouldn't be, it wasn't on gen 4. it was really just a poor design/engineering choice that toyota finally corrected

 

Gen 3 EGR was poor and evidently untested, more's the shame. Gen 3 owners ended up being the testers, and Gen 4 revisions were the outcome.

Wouldn't hurt to pull the throttle body though, see what's lurking beneath. If it looks like a black/shiny mirror (oil pool, courtesy of PCV circuit), further investigation might be in order, and an oil catch can might be useful.

 

- No. EGR problems were fixed over a decade ago.

- No. Toyota uses port AND direct fuel injection. The port injection keeps the intake valves clean.

- With a Prius Plug-in, you want to have your A/C(technically the heat pump) checked more often. The A/C system in the PHEV also keeps the HV battery cool. With all the extra refrigerant lines and seals, it increases the risk of leaks. And it's critical to the long term health of the HV battery to keep it cool. The system will give a hybrid warning light if things get too bad, but an A/C check at 8y/80k is recommended in the official maintenance schedule. Honestly, there just isn't enough data yet to be certain there's any problem(not enough gen5 PHEVs have hit 125k+ to see any trends developing), but it's something to keep an eye on if you own one.

I'll also say that I'm a big supporter of 6m/5k oil changes no matter how little the ICE gets used in a PHEV. That opinion comes from long-time Toyota techs that are much, much smarter and more experienced than me.

My gen5 maintenance schedule:
6m/5k oil change
4y brake fluid(if moisture hasn't exceeded 2.5% yet)
5y/50k both coolants (you can go beyond 50k on the original coolant, but stick to 5y and then strictly 5y/50k after that)
6y/60k transaxle fluid (doubt it will hurt to go longer, but the new TE fluid is still really new, so not much data yet)
8y/80k A/C service(PHEV only) (I might consider dropping that down a bit to 7y/70k or less just to be safe)
change air filters as needed(depends on local conditions)

The brake fluid and transaxle fluid can likely go beyond those numbers, but I feel it's nice to space them out. By having one major fluid change per year, it gets you or a tech underneath the car every 12 months to keep an eye on things(suspension components, rust, fluid leaks, etc.). If you bundle all the maintenance together, it might be a few years between getting underneath for a major inspection, and that gives a lot of time for little problems to become big problems. But that's just my opinion on things.


The known things that can kill a gen5 powertrain as of now are:
- stuck piston rings from sludge (6m/5k oil changes and using a cleaning oil like Valvoline Restore & Protect if it comes in your viscosity; currently yes for 2023-25(0W16) and no for 2026 and up(0W8))
- acidic coolant eating head gasket coating, internal seals, and inverter internals (5y/50k coolant changes to prevent it from getting too acidic)
- overheating the HV batt (maintain A/C system in PHEV and regularly check HV batt filter in HEV)